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The Single UNIX &reg; Specification, Version 2<br>
Copyright &copy; 1997 The Open Group

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<h4><a name = "tag_000_007_083">&nbsp;</a>NAME</h4><blockquote>
isnan - test for a NaN
</blockquote><h4><a name = "tag_000_007_084">&nbsp;</a>SYNOPSIS</h4><blockquote>
<pre><code>

#include &lt;<a href="math.h.html">math.h</a>&gt;

int isnan(double <i>x</i>);
</code>
</pre>
</blockquote><h4><a name = "tag_000_007_085">&nbsp;</a>DESCRIPTION</h4><blockquote>
The
<i>isnan</i>()
function tests whether
<i>x</i>
is NaN.
<p>
On systems not supporting NaN values,
<i>isnan()</i>
always returns 0.
</blockquote><h4><a name = "tag_000_007_086">&nbsp;</a>RETURN VALUE</h4><blockquote>
The
<i>isnan()</i>
function returns non-zero if
<i>x</i>
is NaN.  Otherwise, 0 is returned.
</blockquote><h4><a name = "tag_000_007_087">&nbsp;</a>ERRORS</h4><blockquote>
No errors are defined.
</blockquote><h4><a name = "tag_000_007_088">&nbsp;</a>EXAMPLES</h4><blockquote>
None.
</blockquote><h4><a name = "tag_000_007_089">&nbsp;</a>APPLICATION USAGE</h4><blockquote>
None.
</blockquote><h4><a name = "tag_000_007_090">&nbsp;</a>FUTURE DIRECTIONS</h4><blockquote>
None.
</blockquote><h4><a name = "tag_000_007_091">&nbsp;</a>SEE ALSO</h4><blockquote>
<i><a href="math.h.html">&lt;math.h&gt;</a></i>.
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UNIX &reg; is a registered Trademark of The Open Group.<br>
Copyright &copy; 1997 The Open Group
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